Structural, conductivity and dielectric properties of Li₂SO₄

¹ Department of Physics, College of Sciences, Sri Venkateswara University, Tirupati 517 502, India
² School of Physics, University of Hyderabad, Hyderabad 500 046, India
³ ACRHEM, University of Hyderabad, Hyderabad 500 046, India

^a e-mail: bheemalingam@gmail.com

Received: 21 September 2013
Revised: 14 January 2014
Accepted: 30 April 2014
Published online: 12 June 2014

Abstract

Li₂SO₄ have been synthesized from lithium sulphate monohydrate by melting at 880 °C and slow cooling. The XRD results indicates that the melt cooled Li₂SO₄ is crystallized to monoclinic structure. The AC conductivity (σ_ac) and dielectric relaxation (tan δ) have been measured within the temperature range 170–250 °C and frequency range 100 Hz–120 kHz, respectively. The DC conductivities are conveniently extracted from σ_ac (typical values ∼2 × 10⁻⁷ and ∼2 × 10⁻⁶ S/cm at 200 and 250 °C, respectively) and are fitted to linear Arrhenius plot. The slope of this linear plot leads to an activation energy of 1.10 eV. It is found that the conduction in Li₂SO₄ is mainly through Li⁺. Further, we carried out first principles calculations and obtained the structural and bonding properties of Li₂SO₄. From band structure, Li₂SO₄ is found to be a wide band gap insulator with a band gap of 6.1 eV. The partial density of states reveals the finite states of Li⁺ near to Fermi level, which limits its use of full capacity. This indicates a kinetic barrier for Li ions and electrons ambipolar diffusion.